E′ and B2 center production in amorphous quartz by MeV Si and Au ion implantation

Amorphous SiO2 was implanted with Si+ and Au2+ ions at energies of 4 and 3 MeV, respectively. The doses ranged from 0.3×1017 to 1.5×1017 ions cm−2, and a current density of 30 μA cm−2 was used. The formation of E′ and B2 centers was observed for both ions by optical absorption and electron paramagnetic resonance (for E′ defects) measurements. For Si implantation, there is a saturation of E′-center formation for doses higher than 1.0×1017 Si cm−2; Au implantation produces E′-center annealing for sufficiently high doses. The heating effect due to the relatively high current density induces spontaneous formation of Au nanoparticles already during the ion bombardment. The effect of subsequent thermal annealing in a reducing atmosphere at 600 and 900°C on the E′ and B2 centers was also studied.